1) The various glucagon species will be quantitated and their roles assayed in the control of hepatic regeneration. 2) The currently used amino acid free infusion mixtures will be supplemented with amino acids in animals with clearly defined inslulin/glucagon ratios in a search for initiating factors of hepatic regeneration. 3) Quantitation of hepatic blood flow in the various types of rats being used to clarify the role on non-portal organ substances that initiate or modify hepatic regeneration. BIBLIOGRAPHIC REFERENCES: Voorhees, A.B., Jr., and Price, J.B., Jr.: Extrahepatic portal hypertension. Arch. Surg. 108:338-341, 1974. Whittemore, A., Kasuya, M., Voorhees, A.B., Jr., Price, J.B., Jr.: Hepatic regeneration in the absence of portal viscera. Surgery 77: 419-426, 1975.